A VICS (Vehicle Information and Communication System) and a probe-car information system that collect vehicle information such as speed and time of a vehicle to generate traffic information are known. In the probe-car information system, the running speed and the position of a vehicle on a road where the vehicle has actually run are collected to generate traffic information such as a traffic jam (see, for example, Patent Document 1). In the probe-car information system described in Patent Document 1, a time-series variation in an average speed and a position is calculated based on vehicle information regarding the position of the vehicle and the time thereof to generate traffic jam information. In addition, the vehicle information is sectioned into movement groups at predetermined time intervals so as to be partially overlapped with each other. When the average speed of the movement groups falls within a predetermined speed range, the length of the movement groups is calculated as a traffic jam length or an average speed.
With this configuration, it is possible to eliminate factors irrelevant to a traffic jam, such as the temporal stop of a forward vehicle due to its left turn, right turn, and course change occurring when a pedestrian crosses a road where no traffic signal is installed and the temporal acceleration of the vehicle after the temporal stop, thereby obtaining an exact traffic jam length.
In the probe-car information system described in Patent Document 1, however, standby time at a traffic signal is not eliminated from passing time at a predetermined point such as an intersection. Therefore, the average speed is influenced by the stop of the vehicles at the traffic signal, which results in difficulty in generating high-accuracy traffic jam information.
In light of the above circumstances, the present applicants have proposed a traffic information generation method or the like that eliminates speed reduction by factors other than a traffic jam due to a traffic signal or the like to accurately generate traffic jam information. Patent Document 1: JP-A-2003-281674